#### Current Electricity One Mark Questions with Answer

12th Standard EM

Reg.No. :
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Physics

Time : 00:45:00 Hrs
Total Marks : 25
25 x 1 = 25
1. In a large building, there are 15 bulbs of 40W, 5 bulbs of 100W, 5 fans of 80W and 1 heater of 1kW are connected. The voltage of electric mains is 220V. The minimum capacity of the main fuse of the building will be

(a)

14 A

(b)

8 A

(c)

10 A

(d)

12 A

2. There is a current of 1.0 A in the circuit shown below. What is the resistance of P ?

(a)

1.5 Ω

(b)

2.5 Ω

(c)

3.5 Ω

(d)

4.5 Ω

3. The colour code on a carbon resistor is red - red - black. The resistance of the resistor is?

(a)

$2.2\Omega$

(b)

$22\Omega$

(c)

$220\quad 2.2\Omega$

(d)

$2.2k\Omega$

4. A square aluminum rod is 1 m long and 5 mm on edge. What must be the radius of another aluminum rod whose length is 1 m and which has the same resistance as that of square Aluminum rod?

(a)

1.4 mm

(b)

2.8 mm

(c)

4.2 mm

(d)

5.6 mm

5. Five 3 resistances are arranged in a polygon (5 sides). What is the resistance between any two corners?

(a)

$2.4\Omega$

(b)

$3\Omega$

(c)

$9\Omega$

(d)

$5\Omega$

6. Kirchoff's I law i.e, $\Sigma i=0$ at a junction, deals with the conservation of

(a)

charge

(b)

energy

(c)

momentum

(d)

angular momentum

7. Peltier effect is the converse of

(a)

Joule effect

(b)

Raman effect

(c)

Thomson effect

(d)

Seebeck effect

8. Nichrome wire is used as the heating element because it has

(a)

low specific resistance

(b)

low melting point

(c)

high specific resistance

(d)

high specific resistance

9. The equivalent resistance between A and Bin the figure is

(a)

$15\Omega$

(b)

$7.5\Omega$

(c)

$25\Omega$

(d)

$30\Omega$

10. For which of the following substances, resistance decreases with temperature?

(a)

copper

(b)

platinum

(c)

mercury

(d)

carbon

11. The direction of conventional current is taken as the direction of flow of

(a)

positive charges

(b)

same direction of flow of electron

(c)

opposite to positive charges

(d)

all of these

12. The resistance of mercury is "0" when its temperature is reduced to_____

(a)

4.2°C

(b)

2.4°K

(c)

4.2 K

(d)

-268.8 K

13. 2 A and 3A currents are passed through the heating element of an electrical iron box. The ratio of quantity of heat evolved is_________

(a)

2:3

(b)

3:2

(c)

4:9

(d)

9:4

14. The tolerance of sliver ring in resistors is_________

(a)

5%

(b)

10%

(c)

20 %

(d)

2 %

15. How many electrons constitute current of one ampere?

(a)

6.35 x 10-19

(b)

6.28 x 1018

(c)

6.28 X 1020

(d)

6.25 x 1018

16. The unit of current density is________

(a)

Am-2

(b)

Am2

(c)

A2m-2

(d)

A-2m-2

17. The specific resistance of silver is________

(a)

1.7X10-8$\Omega m$

(b)

1.8X10-7$\Omega m$

(c)

1.6X108$\Omega m$

(d)

16X10-9$\Omega m$

18. The electrical resistivity drops to zero for__________

(a)

conductors

(b)

insulators

(c)

super conductors

(d)

semiconductors

19. For super conductors, the magnetic flux lines are________

(a)

included

(b)

excluded

(c)

0

(d)

maximum

20. Super conductors can be used as storage elements in_________

(a)

TV

(b)

camera

(c)

computers

(d)

computers

21. The tolerance of the resistors are represented by______

(a)

Silver - 10%, Gold - 5%, Red - 2%, Brown - 1%

(b)

Silver - 1%, Gold - 2%, Red - 5%, Brown - 10%

(c)

Silver - 1%, Gold - 10%, Red - 5%, Brown - 2%

(d)

Both (a) and (c)

22. A cell of emf 2.2V sends a current of O.2A through a resistance of 10 n. The internal resistance of the cell is____________

(a)

0.1$\Omega$

(b)

1$\Omega$

(c)

2$\Omega$

(d)

1.33$\Omega$

23. Ohm's law is applicable only for_______________

(a)

complicated circuits

(b)

primary circuits

(c)

simple circuits

(d)

secondary circuits

24. In the case of Wheatstone)s Bridge) the bridge balance condition will be obtained only when____

(a)

the current through the galvanometer is maximum

(b)

the current through the galvanometer is minimum

(c)

the current through the galvanometer is zero

(d)

the current through the galvanometer is infinity

25. In the case of meter bridge) manganin wire is used because it has_________

(a)

low temperature co~fficient of resistance

(b)

high temperature coefficient of resistance

(c)

temperature coefficient of resistance is zero

(d)

temperature coefficient of resistance is maximum